Self-compensating thermostatic apparatus



March 1s, 1941. E, FQNSECA 2,235,216

SELF-COMPENSATING THERMOSTATIC APPARATUS Filed Jan. 5, 1933 ATToRNEY MPatented Mar. 18, 1-941 UNITED STATES SELF-COMPENSATING THERMOSTATICAPPARATUS Edward L. Fonseca, Newark, N. J., assignor'to The WilcolaterCompany, Newark, N. J., a corporation of Delaware Application January 5,193s, serial Nu. 650,255 s claims. `(01.236-15) This invention relatesto thermostat-ic apparatus particularly adapted for regulating rthetemperature within the oven of a gas range or the like with greataccuracy regardless of the extraneous 5 temperatures to which thethermostat is subjected as the result of the operation of the otherburners of the range and which would otherwise render the operation ofthe thermostat inaccurate. Thermostatic apparatus of this nature -isdisclosed in my copending application, Serial No. 575,525, filedNovember 17, 1931, issued December 7, 1937, as Patent No. 2,101,735, andthe present invention is concerned with the saine subject matter.

l5 As indicated in the aforementioned copend-ing application, I mayintroduce the compensating thermostat at any point in the operatingsystem of the heat regulating thermostat and the present invention isdirected to the provision of modications of the self compensating heatregulator disclosed in the said copendin-g application.

In accordance with the invention, I utilize the compensating thermostatas an actuator for transmitting mechanical movements of adjustment orvalve regulation as well yas for providing the thermostatic compensatingvariations in the operating system of the heat regulating thermostat inaccordance with extraneous temperatures. To this end the compensatingthermostat is preferably a bi-metallic strip which may s erve as amotion transmitting lever between the manual adjusting means and thevalve or heat regulating thermostat, or between the heat regulatingthermostat and the valve, or as an element in the manual adjustingtrainincluding the heat regulating thermostat, or the like. In any of thesepositions the compensating thermostat responds to extraneoustemperatures in proportion to the degree thereof to actuate the valve,the

heat regulating thermostat, the adjusting means,

or'a combination of these, the amount which is necessary to compensatefor the disturbing eiects of the extraneous temperatures on the heatregulating thermostat, whereby the latter is, in effect,

insulated against these extraneous temperatures without the use ofactual insulation.

Also in accordance with the invention, I may arrange the apparatus tocompensate for the drop in pressure of the fuel flowing to t-he ovenburneras the result of lighting of one or more of the exterior burners.In order to accomplish this additional compensating eiect, I cause thecompensating thermostat to overcompensate in respouse to temperatureincreases to which the heat regulating thermostat is subjected as theresult of lighting of exterior burners. This overcompensating action ofthe compensating thermostat causes it to open the oven burner valvewider to compensate for .the fuel pressure drop caused by the lightingofthe exterior burner. This over- 5 compensation is additional to thedirect compensat-ion, which insures no change in position of the valveas the result of the eiect of extraneous temperatures on the oventhermostat, but does not compensate for the drop in fuel pressure rel0sulting from the turning on of one or more of the outside burnersproducing the extraneous temperatures. The compensating .thermostat maybe rendered overcompensating simply by making it slightly thinner, if abi-metallic strip is em- 15 ployed, or otherwise procuring .the sameeffect if other forms of .thermostats are employed.

It will be seen that the self-compensating thermostatic apparatus ofthis invention may be mounted anywhere on vany kind of a range or 20stove, whether or not the oven is insulated, without reg-ard to orconsideration of the eiects of extraneous temperatures on .the oven heatregulating thermostat. Accordingly, the apparatus may be mounted on Ithelow inside wall of the 25 oven of the standard console or table top gasrange in close proximity to the adjacentexterior cooking burner with theassurance [that the heat emitted by the exterior burners, and thetemperature fluctuations resulting from the turning 30 on and off of theexterior burners, will not affect the operation of the heat regulatingthermostat. These advantages also simplify installation of the apparatuson the range since it can be placed directly in the fuel supply line anda flexible 35 shaft led thereto from the manual adjusting means whichmay be placed in the most convenient `place, whereby the usual labor,cost, time, and complications of placing the range in service aregreatly reduced. Also, by arranging the com- 40 pensating thermostat toovercompensate, the i'uel pressure drop resulting from operation of theexterior burners is compensated for.

For a. more complete understanding of the invent-ion, reference may bemade .to the accom- 45 panying drawing, in which Figure 1 illustratesone way of mounting one form of the new self-compensating thermostaticapparatus on a gas range of the console type;

Figure 2 is a. cross section through the ap- 50 paratus shown in Figure1,' in which the heat regulating thermostat is a column ofthermo-responsive fluid;

Figure 3 is a cross section through a modified form of the apparatus ofFigures 1 and 2, which is 5;

distinctive in that the heat regulating thermostat is a bi-metallicelement adjustable from a remote point by means of a flexible shaft; andf Figures 4 and 5 illustrate crocs sections through other modified formsof the invention.

Referring to Figure 1 of the drawing, the inner side wall I0 of the ovenII of a conventional style of console range illustrated is only aboutsix inches in height and while it is possible to mount the compactthermostatic control apparatus on this inner wall I0, the adjustinghandle or other mechanism projecting outside of the wall lies directlyabove the exterior cooking burners I2 because of the low height of thewall and consequently the adjusting knob frequently becomes too hot tohandle comfortably. Also, the projection of the mechanism of the controldevice is in the way of and isliable to be injured by cooking utensilsmoved around on the cooking burners I2 if the control device is mountedin the usual place on the side wall I0 of the oven Il. Furthermore,whether the control device is mounted in the usual place on the sidewall l0 of the oven above the exterior burners I2 as illustrated, orbelow them, it is subject to extraneous temperatures emitted by theexterior cooking burners I2 and the heat regulating thermostat of thedevice responds to this false extraneous heat to actuate the oven burnervalve so that the temperature of the oven burner iluctuates and does notmaintain the temperature of the oven at the degree pre-registered by theadjusting knob, and this is especially so when the exterior cookingburners are turned on and oi during the operation of the oven, as isfrequently the case.

The thermostatic apparatus of this invention permits practically anydesired arrangement and Figure 1 illustrates an example of this feature,the apparatus being located beneath the fuel supply manifold |3 and theexterior burner top I2, and behind the front panel |4, so that in useall pipe connections are hidden and only the adjusting knob or dial I5is visible in addition to the cocks for the several burners, includingcock I6 of the oven burner I1, which is connected to the manifold I2 bypipe I9 through the thermostatic apparatus |8.` The cooking top of therange is thus free of damageable obstructions,

In the form of thermostatic apparatus |8 illustrated in Figures 1 and 2,the valve body 20 may be suitably supported, such as by the supply pipe2| leading from the oven fuel cock I6. The valve body 28 contains a fuelintake chamber 22, with which pipe 2| communicates and a fuel outletchamber 23, with which outlet pipe I9 communicates. The inletchamber 22and the outlet chamber 23 are connected by passage 24 controlled byvalve 25, which is normally urged to- Ward closed position by a spring26 seated at one end in cap 21. An adjustable needle valve 28 bypasses asmall supply of gas from inlet chamber 22 through passage 29 controlledby the needle Valve 28 into outlet chamber 23, so that the oven burnerI1 is supplied with a small but continuous supply of gas when the cockI6 is open, even if the valve 25 is closed, in order that the ovenburner |1 will not be extinguished unintentionally. Needle valve 28 isaccessible for adjustment upon removal of cap 3|.

Located within the oven at a point which is representative of thetemperature thereof, is a bulb 32 which is connected by a capillary tube33 to a chamber 34 formed between the exterior surface of flexible metalbellows 35 and the interior surface of cup 36, which is sealed by gasket31 over an opening in the va\lye body 20 communieating with the fuelinlet chamber 22. The joint between the bellows 35 and the cup 36 issealed by means of ring 38. A perforated disc 39 is interposedbetweenthe cup and the valve body 28, a gasket 40 being inserted betweenthe disc 39 and the valve body 20 to seal the joint. The space 34between bellows 35 and cup 36, the capillary tube 33 and the bulb 32vjointly form a `continuous sealed column which contains a suitablethermoresponsive liquid having a high boiling point and negligible vaporpressure at the working temperatures to which it is subjected.

The disc 39 is perforated and also serves as a guide for a rod 42secured at one end to the cap 43 of the bellows 35 and threaded at itsother end 44. A spring 45 is interposed between the bellows cap 43 andthe disc 39 and tends to keep the bellows 35 expanded and normally urgesrod 42 to the left, as seen in Figure 2. A nut 46 is screwed on thethreaded end 44 of rod 42 and is provided with lateral keys 41 whichslide in corresponding slots or keyways'in yoke 48 having a sealingconical seat 49 which prevents the escape of fuel at this point. Yoke 48is formed on the end of shaft 50 projecting out of the valve body 20 andcarrying at its free end a knob 5| having a scale 52 which cooperateswith a suitable index on the front panel I4 or other surface of therange. A spring 53, interposed between valve body 20 and a collar 54 onshaft 50, holds sealing cone 49 securely against its seat and alsoserves to lock knob 5| in any adjusted position. It will be seen thatrotation of the knob causes nut 46 to screw on or off of the threadedend 44 of rod 42, so that the position thereof varies with respect tothe bellows 35.

Rockingly seated on nut 46 and bifurcated to accommodate the reduced endof the latter, is a bi-metallic compensating thermostat 55 pivotedadjacent its center on fulcrum 56 and having an opening in its oppositeend for the reception oi' the reduced end 51 of the stem 58 of valve 25.The bifurcated end of the compensating thermostat 55 is formed into aV-shape which rocks with a knife blade action on the shoulder 4| of nut46. Thus, the compensating thermostat 55 not only acts as a thermostatbut also as a motion-transmitting lever between the bellows 35 and thevalve 25, the opposing springs 45 and 26 holding the compensatingthermostat 55 firmly and steadily in any adjusted position. For example,as the bellows 35 is compressed in response to the expansion of thethermo-responsive liquid column in accordance with an increase in thetemperature in the oven rod 42 is moved to the right as seen in Figure 2to actuate nut 46 so that compensating thermostat 55 pivots about itsfulcrum 56 to permit spring 26 to move valve 25 toward closed position.Conversely, as the thermoresponsive liquid column contracts in responseto a decrease in temperature in the oven rod 42 moves toward the left,as seen in Figure 2, under the influence of spring 45, so thatcompensating thermostat 55 is moved in a counter-clockwise directionabout fulcrum 56 to open valve 25. Adjustment of knob 5| regulates valve25 because nut 46 is either advanced or retracted along rod 42 and inturn transmits motion through compensating thermostat 55 to valve 25.

When the oven is in operation and none of the exterior burners I2 is inuse to influence the thermo-responsive liquid and there is no unusualexterior temperature condition, the thermostatic apparatus operates in amanner readily understood, compensating thermostat 55 acting simply as amotion-transmitting means between the bellows 35 and the valve 25 in themanner described. However, should the user of the range turn on one ofthe exterior burners l2, lthe heat emitted thereby by radiation,conduction, or convection, would inuence the thermo-responsive liquidcolumn because of the proximity of the latter to the source of theextraneous heat. The thermo-responsive liquid column `-would accordinglyrespond to this extraneous heat by expanding to move valve 25 towardclosed position, so that the fuel supply to the oven burner wouldordinarily be reduced unnecessarily since this change in the supply offuel `was not caused by any change in oven. temperature. Accordingly,the temperature of the oven would not be constant and this conditionwould be aggravated by the turning on of additional burners and also byturning burners'oi, in a manner readily understood. However, thecompensating thermostat 55 responds to these extraneous temperatures by-flexing proportionately so that whenever the thermostatic columnexpands in response to these extraneous temperatures and tends to movevalve 25 toward closed position, the compensating thermostat 55 exes inthe same direction in response to the extraneous temperature to holdvalve 25 in the proper position, since it opens the valve 25 the samedegree that the thermo-responsive uid column closes the valve inresponse to these extraneous temperatures. Conversely, any reduction intemperature, to which the thermostatic uid column would ordinarilyrespond by contracting to open valve 25 further, is nulliiied by thecompensating thermostat 55, which accordingly flexes an equal amount inthe same direction. The compensating thermostat 55 also responds tochanges in extraneous temperatures other than those caused by theturning on or off of the exteriorcooking burners I2, so that the heatregulating thermostat regulates the fuel supply only in response to thetemperature conditions in the oven. v

Figure 3 illustrates a modified form of the selfcompensating thermostatof Figure 2 in that the thermo-responsive liquid column is replaced by abi-metallic thermostatic strip 59, which is anchored at one end to thevalve casing 20' and is connected at its other end to a rod 42 which isslidably mounted through the wall of the casing 29 and projects into thefuel inlet chamber 22. The inner end of rod 42' is threaded in nut 46',

which is slidably mounted in the yoke 48 of shaft 56', adjustable by aflexible shaft 60 rotated by knob l A lever 4l' xed on rod 42 andslidable on fixed pin 45' holds rod 42' against rotation. A coil spring53' between valve casing 20' and collar 54' locks shaft 50' in anyposition to which it has been adjusted by knob 5l and also serves toseal the conical portion of yoke 48 in its seat against the escape offuel. ment of Figure 2, the compensating thermostat 55 is connected atone end to nut 46' and at the other end to valve 25', being pivoted atits center on fulcrum 56'.

The inlet chamber 22 of the valve casing 20 is connected to the sourceof fuel supply in the usual way and the outlet chamber 23 is connectedby pipe I9' to the burner of the oven. In order to be responsive to thetemperature within the oven the heat regulating thermostat 59 ispreferably introduced through an opening in the wall I9 of the oven Il,and in order to be readily accessible, the adjusting knob 5| ispreferably As in the arrangeplaced at a convenient point on panel I4remote f its fulcrum 56 to move valve 25 toward open' position. In theevent that any of the exterior cooking burners I2 is turned on, thecompensating thermostat 55' flexes in response to the resultingextraneous heat so as to nullify the additional movement imparted to theheat regulating thermostat 59 by this extraneous heat, so that theposition of valve 25 is not changed and the oven is maintained atconstant temperature. Thus, the compensating thermostat 55in thisarrangement, as in the arrangement of Figure 2, in effect insulates theheat regulating thermostat from extraneous temperatures.

A somewhat different arrangement is illustrated in Figure 4. The valvebody 62 is mounted on the oven wall I0 with a portion projecting Atherethrough, so as to be subjected to the temperature Within the oven.The fuel inlet chamber 63 of the valve body 62 is supplied with fuelfrom the manifold I3 in the usual way and communicates with outletchamber 64 through passage 65 which is controlled by valve 66 normallyurged toward closed position by spring 61. A

push rod 68 engages the valve 66 and is slidably mounted in a bushing 69secured to valve body 62. The outer end of push rod 68 engages one endof heat regulating bi-metallic thermostat 10 which isfulcrumed at 1| andengages with its opposite end the actuating rod 12, which is slidablethrough the valve body 62 and engages compensating bi-metallicthermostat 13 at a point between. its fixed end 14 and its opposite end,

which is engaged by a screw 15 rotatable by a flexible shaft 16connected to adjusting knob 11. It Will be noted that the heatregulating thermostat 19 lies within the oven wall I0 and thecompensating thermostat 13 lies outside of it.

The knob 11 may be placed at any convenient point such as on the panelI4 and manipulation' thereof by the user of the range is communicated byflexible shaft 16 to screw 15, which in turni' moves compensatingthermostat 13 about its pivot 14 and this thermostat, by means ofactuating rod 12, pivots heat regulating thermostat 10 about `itsfulcrum 1| to move valve 66 to its initial open position. 'I'he heatregulating thermostat 10 maintains the temperature of the oven to thedegree pre-registered by knob 11. In the event that extraneous heats areset up by operation of the exterior cooking burners I2, the compensatingthermostat 13 responds by flexing to the left, as seen in Figure 4, tocompensate for the equivalent exure of heat regulating thermostat 19 tothe right in response to the extraneous heats. Thus, the false responseof the thermostat 10 which would ordinarily result in movementof valve66 toward closed position, is nullied by the action of compensatingthermostat 14.

Figure 5 illustrates still another form of the invention in which theheat regulating thermostat 18 which lies within the wall l0 of theoven,l

is adjustable about its fulcrum 'I9 by adjusting screw l0, in accordancewith the desired oven temperatures, and actuates push rod 8| to causecompensating thermostat 82 to open valve 83. The heat regulatingthermostat 18 responds to variations in the temperature of the oven toactuate valve 83 through the operating train just described to maintainthe oven at the proper predetermined temperature set by adjusting screw80. The compensating thermostat ,82, in response to extraneous heats,flexes to the right, as seen in Figure 5, to compensate for thecorresponding flexure of the heat regulating thermostat 18 to the leftin response to these extraneous heats. y Any of the modifications of theinvention may be arranged to compensate for the drop in fuel pressure,which accompanies the increase in extraneous temperature resulting fromthe turning on of one or more of the exterior burners I2 located betweenthe supply and the oven burner, by making the compensating thermostats55, 55', 13 or 82 slightly thinner, so that they will overcompensate,with the result that instead of only compensating for the effects on theheat regulating thermostat of the increase in extraneous temperatures,the corresponding oven fuel valve 25, 25', 66 or 83 is opened wider tosupply a sufdciently greater volume of the fuel at lower pressure as isnecessary to compensate for its drop in pressure. Other equivalent waysof causing the compensating thermostat to over compensate may beemployed with equal facility, whether or not the thermostat is of thebimetallic strip type or some other equivalent form.

It will be seen that in each of the modifications of the inventionillustrated and described, all eiects of extraneous or local heats fromany cause are compensated for by the compensating thermostat, which hasbeen previously calibrated accordingly. This self-compensation of theapparatus permits the'mounting thereof anywhere on any range withoutregard to or consideration of the effects of extraneous temperaturesthereon. Itwill also be seen that in each of the arrangementsillustrated and described the compensating thermostat acts as amotion-transmitting means as Well as a thermostat and thus may besubstituted Vin place of the corresponding element in standard heatregulating apparatus to convert it into a self-compensating devicewithout requiring reconstruction or any extra parts. The severalarrangements illustrated and described herein also indicate that thecompensating thermostat may be placed in practically any position withregard to the valve, the adjusting means, or the heat regulating thermoystat, and although particular arrangements and structures have beenillustrated and described, it is to be understood that the invention isnot limited thereby, but is susceptible of various changes of form anddetail within its scope.

I claim:

1. In a thermostatic apparatus for controlling the temperature of a gasrange oven, the combination of a gas supply valve for the oven burner, athermostat responsive to the temperature of the oven, a-thermostaticlever pivoted intermediate its ends and connected at one end to thethermostat and at the other end to the valve and responsive toextraneous temperatures for modifying the setting of the valve, andmeans for adjusting the thermostati lever about its pivot independentlyof the thermostat.

2. In a thermostaticregulator for the heater of the oven of a. range,the combination of means for controlling the heater, a thermostatresponsive to the temperature of the oven, an operative connectionbetween the thermostat and. the means including a second thermostatresponsive to temperatures outside the oven for modifying the actuationof the means by the rst thermostat, and means for adjusting the secondthermostat to vary the relation between said means and the firstthermostat.

3. In a thermostatic regulator for the heater of the oven of a range,the combination of means for controlling the heater, a thermostatresponsive to the temperature of the oven, operative connections betweenthe thermostat and the means including a bimetallic lever responsive totemperatures extraneous to the oven for modifying the actuation of themeans by the thermostat, and a handle for adjusting the lever to varythe relation between said means and the thermostat.

4. In combination with a range having a heating device in the oven andan exterior heating device adjacent the oven, an element for controllingthe supply of a heating medium to the oven heating device, a thermostathaving a thermo-sensitive part in the oven for controlling the elementin accordance with temperature changes in the oven, Ia connectionbetween the thermostat and said element including a second thermostatoutside of the oven and responsive with the first thermostat to heatemitted by the exterior heating device and operable to modify thesetting of the element to compensate for the effect of the heat of theexterior heating device on the rst thermostat, and a handle foractuating the rst thermostat and thereby adjusting the control elementthrough said thermostats.

5. In a thermostatic apparatus for controlling the temperature of anoven, the combination of a casing, a rod extending through the front ofthe casing and rotatable therein, a thermostat at the rear end of thecasing in axial alignment with the rod, an actuator in the casingbetween the rod and thermostat and operatively connected to thethermostat and adjustable relative thereto by rotation, of the rod, vabimetallic lever pivoted intermediate its ends in the casing andextending laterally from the axis of the rod, one end of the lever beingengaged by the actuator, and a control element olfset laterally from theaxis of the rod and connected to the opposite end of the lever, thelever being operable to transmit motion of the rst thermostat andactuator to the control element and being adjustable by rotation of therod to change the setting of the control element.

6. In a thermostatic apparatus for controlling the temperature of anoven, the combination of a device through which a medium for heating the-oven is supplied, a plurality of thermostats operatively connected tothe device, one of said thermostats being responsive to the temperatureof the oven and acting through said device to shut down the supply ofthe heating medium upon a rise of temperature, and the other thermostatbelng responsive to temperature outside the oven and acting through saiddevice to'increase the supply of heating medium upon a rise oftemperature, one of said thermostats being a bimetallic elementconnected at a point intermediate its ends to the device, and a handleoperatively connected to one of the vthermostats for adjusting saidthermostats and the devlceas a unit.

the temperature of an oven, the combination o! a device through which amedium for heating the oven is supplied, a plurality of thermostatsoperatively connected in series to the device, one o! said thermostatsbeing responsive to temperature changes in the oven and acting throughsaid device to shut down the supply of heating medium upon a rise intemperature. and the other thermostat being responsive to temperaturechanges outside the oven and acting through said device to increase thesupply of heating medium upon a. rise in temperature, said lastthermostat being a bimetallic element connected at a point intermediateits ends to said device, and a handle operatively connected to at leastone end of the second' thermostat for adjusting the second thermostatand said device as a unit.

8. In a thermostatic apparatus for controlling the temperature in anoven, or the like, having a. heating device, thel combination of anelement for controlling the supply of a heating medium to said device. athermostat to the temperature oi the oven. a thermostatic lever pivotedintermediate its ends and connected at one'end to the thermostatandattheotherendtosaid control element and to extraneous temperaturesfor modifying the setting of the control element, and means foradjusting the thermostatic lever about its pivot independently of thethermostat.

9. In combination with a cooking range having a heater in the oven andan exterior heater adjacent the oven, a casing mounted adjacent the ovenwall and having a device for controlling the supply of a heating mediumto the oven heater, a thermostat on the casing having a part projectingthrough the wall of the oven and responsive 10 to the oven .temperatureand acting through said device to reduce the supply of heat upon a. risein the oven temperature, a second thermostat on the casing locatedoutside o! the oven and connected .to the irst thermostat and throughwhich .mo- .15 tion from the iirst thermostat is transmitted to thecontrol device, the lsecond thermostat being operable .to compensate forthe eiect of the heat of the exterior heater on the iirst thermostat andacting through said device to increase the heat 20 supply upon a rise intemperature due to the exterior heater, and a handle connected to one ofthe `thermostats for adjusting both thermostats and the control deviceas a unit, said thermostats and adjusting means jointly constituting thecon- 25 trol means for said device.

EDWARD L. FONSECA.

